991900810 has 16 divisors (see below), whose sum is σ = 1833676776. Its totient is φ = 386036928.

The previous prime is 991900801. The next prime is 991900841. The reversal of 991900810 is 18009199.

It can be written as a sum of positive squares in 4 ways, for example, as 668584449 + 323316361 = 25857^2 + 17981^2 .

It is a super-2 number, since 2×991900810² = 1967734433757312200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a self number, because there is not a number n which added to its sum of digits gives 991900810.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1340037 + ... + 1340776.

Almost surely, 2^991900810 is an apocalyptic number.

991900810 is a deficient number, since it is larger than the sum of its proper divisors (841775966).

991900810 is a wasteful number, since it uses less digits than its factorization.

991900810 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2680857.

The product of its (nonzero) digits is 5832, while the sum is 37.

The square root of 991900810 is about 31494.4568138585. The cubic root of 991900810 is about 997.2929484846.

The spelling of 991900810 in words is "nine hundred ninety-one million, nine hundred thousand, eight hundred ten".